Coupling of Nitrous Oxide and Methane by Global Atmospheric Chemistry

Prather, Michael J.; Hsu, Juno

doi:10.1126/science.1196285

Cited by 78 publications

(77 citation statements)

References 15 publications

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“…Recent studies suggest that increases in N 2 O release to the atmosphere could influence the methane cycle through ozone reduction and an increase in the production of •OH (25). This production could partially offset increases in methane concentrations, as modeled here, which result from increased marine DOC concentrations and elevated atmospheric CO fluxes.…”

Section: Modelmentioning

confidence: 82%

“…Most atmospheric chemistry models dealing with methane oxidation in the deep past have modeled it as a steadystate process because of methane's short residence time. However, the effective lifetime of a methane perturbation in chemically coupled systems is longer than the steady-state residence time of methane as shown for the recent anthropogenic methane increase (24,25). When dealing with large perturbations as studied here, this difference becomes even more important.…”

Section: Modelmentioning

confidence: 85%

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Towards a quantitative understanding of the late Neoproterozoic carbon cycle

Bjerrum

Canfield

2011

Proc. Natl. Acad. Sci. U.S.A.

120

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The cycles of carbon and oxygen at the Earth surface are intimately linked, where the burial of organic carbon into sediments represents a source of oxygen to the surface environment. This coupling is typically quantified through the isotope records of organic and inorganic carbon. Yet, the late Neoproterozoic Eon, the time when animals first evolved, experienced wild isotope fluctuations which do not conform to our normal understanding of the carbon cycle and carbon-oxygen coupling. We interpret these fluctuations with a new carbon cycle model and demonstrate that all of the main features of the carbonate and organic carbon isotope record can be explained by the release of methane hydrates from an anoxic dissolved organic carbon-rich ocean into an atmosphere containing oxygen levels considerably less than today.carbon isotope excursion | carbon monoxide | Shuram-Wonoka anomaly | earth evolution | atmospheric chemistry T he Neoproterozoic Eon was one of the most dynamic, yet enigmatic, times in Earth history. The Eon saw the breakup of super continent Rodinia and was punctuated by several glacial episodes, some of which were global in extent (1). The Eon saw the evolution and expansion of the first animals on Earth (2), as well as a rise in atmospheric oxygen and a major oxygenation of the deep ocean (3, 4). The isotopic composition* of carbonate (δ 13 C IC ) in sedimentary rocks reveals some of the largest isotope fluctuations in marine dissolved inorganic carbon (DIC) in Earth history (e.g., 4-6). Such isotope fluctuations are considered to reflect dynamics in the carbon cycle, and they have been used to reconstruct the history of atmospheric oxygen (e.g., 7, 8).The Neoproterozoic δ 13 C IC record, however, reveals excursions to less than mantle values (< − 5‰), and the assumed input value to the oceans (5, 9) ( Fig. 1). Prolonged negative δ 13 C IC excursions such as these cannot be explained by our normal understanding of the carbon cycle (e.g., 10, 11). While a diagenetic origin has been advocated to explain these excursions (12, 13), we will show that the major features of the carbon isotope records are consistent with a seawater origin through the action of the carbon cycle.Indeed, a nondiagenetic origin for the carbon isotope excursion is supported by the fact that in individual regions, an excursion may be observed over 100's of kilometers, mappable to the same stratigraphic horizon, and with isotope trends independent of sediment lithology (e.g., 14-16). The lateral extent and stratigraphic consistency of these excursions is difficult to reconcile with a diagenetic origin. Furthermore, modeling shows that the extent of isotopic alteration during diagenesis is highly dependant on the mineralogy of both the initial and the altered sediment (12). Isotope trends, however, transcend these differences (e.g., 6, 14, 17), further arguing against a diagenetic origin for the isotope signals.Many of the large Neoproterozoic isotope excursions display a relationship between the 18 O and 13 C of carbonate, which is...

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Section: Modelmentioning

confidence: 82%

Section: Modelmentioning

confidence: 85%

Towards a quantitative understanding of the late Neoproterozoic carbon cycle

Bjerrum

Canfield

2011

Proc. Natl. Acad. Sci. U.S.A.

120

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“…The rapid increase of the concentration of carbon dioxide in the atmosphere in the last four decades may be due to the human consumption of large quantities of fuels, especially the oil consumption. Atmospheric nitrous oxide concentration in the similar period of years (nearly 150 years), from 270 ppb (parts per billion) increased to 310 ppb (Prather and Hsu, 2010;Aneja et al, 2009). One major reason for this increase may be the use of chemical fertilizers in agriculture and the global fuel consumption, especially oil use.…”

Section: Increased Concentrations Of the Most Important Greenhouse Gamentioning

confidence: 99%

The Future Crops for Biofuels

Li¹,

Sun²

2011

Economic Effects of Biofuel Production

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“…for CHF 3 ), but for those long-lived gases with chemical feedbacks this does not hold (e.g. for N 2 O [15] ). In the former case the steady-state lifetime for any surface emissions is very close to the e-fold time scale for decay of a perturbation.…”

Section: Introductionmentioning

confidence: 99%

“…This simplification fails for short-lived species, [16][17][18][19] but the lifetime remains the correct integrating factor if one scales the pulse to the steady-state pattern. A correction from lifetime to perturbation lifetime is correctly applied when calculating the environmental effect of additional emissions, such as the global warming potentials for gases with chemical feedbacks like CH 4 and N 2 O, [4,8,15,20,21] but the time scale of those effects cannot always be represented by a simple e-fold as in most assessments. [13,14,22,23] The use of metrics involving time is powerful, can be straightforward and follows directly from the different ways of defining them.…”

Section: Introductionmentioning

confidence: 99%

A perspective on time: loss frequencies, time scales and lifetimes

Prather

Holmes

2013

Environ. Chem.

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Environmental context. The need to describe the Earth's system or any of its components with a quantity that has units of time is ubiquitous. These quantities are used as metrics of the system to describe the response to a perturbation, the cumulative effect of an action or just the budget in terms of sources and sinks. Given a complex, non-linear system, there are many different ways to derive such quantities, and careful definitions are needed to avoid mistaken approximations while providing useful parameters describing the system. Abstract. Diagnostic quantities involving time include loss frequency, decay times or time scales and lifetimes. For the Earth's system or any of its components, all of these are calculated differently and have unique diagnostic properties. Local loss frequency is often assumed to be a simple, linear relationship between a species and its loss rate, but this fails in many important cases of atmospheric chemistry where reactions couple across species. Lifetimes, traditionally defined as total burden over loss rate, are mistaken for a time scale that describes the complete temporal behaviour of the system. Three examples here highlight: local loss frequencies with non-linear chemistry (tropospheric ozone); simple atmospheric chemistry with multiple reservoirs (methyl bromide) and fixed chemistry but evolving lifetimes (methyl chloroform). These are readily generalised to other biogeochemistry and Earth system models.

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Coupling of Nitrous Oxide and Methane by Global Atmospheric Chemistry

Cited by 78 publications

References 15 publications

Towards a quantitative understanding of the late Neoproterozoic carbon cycle

Towards a quantitative understanding of the late Neoproterozoic carbon cycle

The Future Crops for Biofuels

A perspective on time: loss frequencies, time scales and lifetimes

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